Flexible membrane weir

ABSTRACT

A flexible membrane weir comprises a lengthy flexible outer bag arranged in a widthwise direction of a water channel and provided with a fluid supply-drain means, and a lengthy flexible inner bag accommodated and arranged in the interior of the flexible outer bag and provided with another fluid supply-drain means.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a flexible membrane weir inflating or deflating by supply or drain of a fluid such as air, water or the like, and more particularly to a flexible membrane weir not completely keeping the function as a weir even if abnormal state is caused in a part of the weir.

2. Description of the Related Art

Recently, a flexible membrane weir called as a rubber dam inflating and deflating by the supply and drain of a fluid such as air water or the like is widely used because it is simple in the laying and cheap in the cost. The flexible membrane weir is arranged on a river bed or the like so as to direct a longitudinal direction of the flexible membrane body to a widthwise direction of a water channel and inflated by supplying the fluid to an interior of the flexible membrane body to stem water in the water channel. Then, it is deflated by draining the fluid from the interior of the flexible membrane body to allow to flow the stemmed water toward downstream side.

The flexible membrane weir may be accidentally deflated due to the breakage of the flexible membrane body based on collision with bounding stone, driftwood, other floating objects and the like. In this case, the function as the weir is damaged and hence it is also envisaged that a greater amount of water stemmed by the flexible membrane weir violently flows from the upstream side to cause serious damage at the downstream side. Although the flexible membrane weir was used at a small size in the restricted applications such as agricultural water and the like, the role thereof is recently enlarged to applications such as urban disaster prevention, water space and the like, and hence the size becomes larger and the risk due to the accidental deflation is increasing accompanied therewith. For this end, as shown by a section view in FIG. 6, there is proposed a double structure of the flexible membrane weir, in which the flexible membrane weir 31 comprises a non-airtight outer layer rubber 33 and an airtight inner tube 34 enveloped with the outer layer rubber 33 and inflating and deflating through the supply and drain of the fluid, and the damage of the inner tube 34 due to the collision with the bounding stone or the like can be prevented by the outer layer rubber 33 to avoid the deflation of the weir and eliminate the fear of causing flood disaster or the like (see JP-A-H11-303049).

Even if the double structure is adopted in the flexible membrane weir as disclosed in the above patent document, however, there is still existent a possibility that the damage of the inner tube is caused by the impaling of the driftwood passing through the outer layer rubber (or flexible membrane), cantrip and the like.

SUMMARY OF THE INVENTION

It is, therefore, an object if the invention to solve the above problems of the conventional technique and to provide a flexible membrane weir capable of temporarily preventing the deflation due to the accidental breakage of the flexible membrane to ensure the safety.

In order to achieve the above object, the invention lies in a flexible membrane weir comprising a lengthy flexible outer bag arranged so as to extend in a widthwise direction of a water channel and inflating by supplying a fluid into an inside thereof and deflating by draining the fluid from the interior thereof, and a lengthy flexible inner bag accommodated and arranged in the interior of the flexible outer bag and capable of arranging fluid supply and drain independently of the fluid supply and drain in the flexible outer bag.

In a preferable embodiment of the invention, the flexible inner bag has a height corresponding to 0.5-0.9 times a height of the flexible outer bag, and ensures an internal pressure higher than that of the flexible outer bag. Preferably, the flexible inner bag has a differential pressure of 2-10 kPa with respect to the flexible outer bag.

In the flexible membrane weir according to the invention, even if cracks are caused in a part of the flexible outer bag to leak the fluid from the interior thereof, the deflation of the weir is not caused due to the presence of the flexible inner bag and a certain degree of the weir height can be kept. Therefore, there can be avoided a situation that water stemmed at the upstream side violently flows down to cause serious damage at the downstream side.

Also, in the flexible membrane weir according to the invention, the flexible inner bag is accommodated and arranged in the interior of the flexible outer bag, so that the occurrence of V-shaped notch such as local fall-down or the like can be suppressed by the flexible inner bag as a core body.

Furthermore, as the cracks are generated in the flexible outer bag to leak out the fluid from the interior thereof, the flexible outer bag is deflated to copy the form of the flexible inner bag, so that the abnormal state of the outer bag can be found by visual monitoring to immediately take measures.

Moreover, in the flexible membrane weir according to the invention, the flexible inner bag is fixed to a river bed through anchor bolts arranged on the river bed, so that even if the flexible outer bag is largely broken, the flexible inner bag never comes out toward the downstream side.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a flexible membrane weir according to the first embodiment of the invention;

FIG. 2 is a section view taken along a line A-A of FIG. 1;

FIG. 3 is a perspective view partly shown in section of the flexible membrane weir according to the first embodiment of the invention;

FIG. 4 is a section view of another flexible outer bag;

FIG. 5 is a section view of a flexible membrane weir according to the second embodiment of the invention; and

FIG. 6 is a section view of the conventional flexible membrane weir having a double structure of an outer layer rubber and an inner tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the invention is explained with reference to the accompanying drawings. FIG. 1 is a front view of the flexible membrane weir according to the first embodiment of the invention, and FIG. 2 is a section view taken along a line A-A of FIG. 1, and FIG. 3 is a perspective view partly shown in section of this flexible membrane weir.

As shown in FIG. 1, the flexible membrane weir 1 comprises a lengthy flexible outer bag 3 arranged so as to extend in a widthwise direction of a water channel 2 (direction of arrow W) for opening and closing the water channel to intake service water, which inflates through the supply of a fluid such as air, water or the like to the interior thereof and deflates through the drain of the fluid from the interior as shown in FIGS. 2 and 3, and a lengthy flexible inner bag 4 accommodated and arranged in the interior of the flexible outer bag 3 and capable of arranging another fluid supply and drain.

In FIGS. 1-3, two rows of anchor bolts 13, 14 are disposed on a river bed concrete 10 and both slope portions 11 at predetermined intervals over a full length in the widthwise direction of the water channel (direction of arrow W). The flexible outer bag 3 is hermetically fixed onto the river bed concrete 10 and slope portions 11 by passing holes for fixation of an overlapped portion 17 of the flexible outer bag 3 and a fixing bracket 15 through the anchor bolts 13 and screwing nuts 21. Also, the anchor bolts 14 are passed through holes formed in the flexible outer bag 3. The flexible inner bag 4 is hermetically fixed onto the river bed concrete 10 and slope portions 11 inside the flexible outer bag 3 by passing holes for fixation of an overlapped portion 19 of the flexible inner bag 4 and a fixing bracket 16 through the anchor bolts 14 and screwing nuts 22.

The flexible outer bag 3 is formed by overlapping two lengthy flexible membranes to each other and bonding both end portions of these membranes with each other in a direction perpendicular to a longitudinal direction of the membrane along the longitudinal direction through vulcanization, The overlapped portions 17, 18 are joint portions after the vulcanization. Also, the flexible outer bag 3 is provided on a longitudinal one end portion with a supply-drain means (not shown) for supplying a fluid such as air, water or the like into an interior of the outer bag 3 or draining the fluid from the interior thereof, whereby the flexible outer bag 3 is inflated or deflated through the supply or drain of the fluid with the fluid supply-drain means.

Similarly, the flexible inner bag 4 is formed by overlapping two lengthy flexible membranes to each other and bonding both end portions of these membranes with each other in a direction perpendicular to a longitudinal direction of the membrane along the longitudinal direction through vulcanization. The overlapped portions 10, 20 are joint portions after the vulcanization. Also, the flexible inner bag 4 is provided on a longitudinal one end portion with a supply-drain means (not shown) for supplying a fluid such as air, water or the like into an interior of the inner bag 4 or draining the fluid from the interior thereof independently of the supply-drain means for the flexible outer bag 3, whereby the flexible inner bag 4 is inflated or deflated through the supply or drain of the fluid with the fluid supply-drain means independently of the flexible outer bag 3. The flexible inner bag 4 is disposed in the interior of the flexible outer bag 3 at a deflated state by draining the fluid.

The flexible membrane weir 1 is inflated by supplying the fluid into each of the flexible outer bag 3 and the flexible inner bag 4 through the supply-drain means to expand the bags 3 and 4 to thereby stem water in the water channel 2, while it is deflated by draining the fluid from each of the outer bag 3 and the inner bag 4 to shrink these bags 3 and 4 to thereby flow water stemmed in the water channel 2 toward the downstream side.

It is desirable that the height of the flexible inner bag 4 is about 0.5-0.9 times the height H of the flexible outer bag 3 (weir height) and that an internal pressure higher than that of the flexible outer bag 3 is ensured to keep the form of the inflated flexible inner bag 3 even in the flexible outer bag 3. For example, when the flexible inner bag 3 has a height of 0.8H, even if the flexible outer bag 3 is broken, the weir height is merely lost by 0.2H to outpour the stemmed water, but the scale of the flooding at the downstream side can be made small. Therefore, it is desirable to design the size of the flexible inner bag 4 by conducting an adequate estimation to verify an acceptable water dosage flowed out form the stemmed water for the weir height H.

As the internal pressure of the flexible outer bag 3 lowers below a certain level, the local fall-down such as V-notch is caused and hence the weir height of the flexible membrane weir lowers at one stroke and also there is caused a problem that the portion at the downstream side of the V-notch place is scoured to change the form of the water channel or the like. In the usual flexible membrane weir, the V-notch is generated as the weir height lowers to about 0.5-0.7H, which constitutes the constraint in the control of the weir height. In the invention, the flexible inner bag 4 is accommodated and arranged in the interior of the flexible outer bag 3, so that even if the flexible membrane weir is accidentally deflated, the safety is ensured, and the flexible inner bag 4 always serves as a core body to delay the occurrence of V-notch and even when the weir height lowers to about 0.5-0.7H, the flexible inner bag 4 as the core body can suppress the occurrence of V-notch. Furthermore, after the internal pressure of the flexible outer bag 3 is lowered to render the weir height into the height of the flexible inner bag 4, when the internal pressure of the flexible inner bag 4 is controlled so as to have a differential pressure of 2-10 kPa with respect to the flexible outer bag, it is possible to control the water level to an extent larger than that of the conventional flexible membrane weir consisting only of the flexible outer bag, and the safety is further improved.

Also, nylon fiber-reinforced rubber or the like is used as a flexible membrane for the flexible outer bag 3 and the flexible inner bag 4.

Moreover, the first embodiment is also applied to a case that the flexible inner bag is added to a place previously provided with the flexible membrane weir consisting of the flexible outer bag. In this case, it is necessary to form holes passing anchor bolds for the fixation of the flexible inner bag in the flexible outer bag, but if the damage due to the formation of the holes is small, the flexible outer bag can be used as it is after the formation of the holes.

In addition, as shown in FIG. 4, two rows of anchor bolts 26, 27 are disposed on the river bed concrete 10 at given intervals over full length in the widthwise direction of the water channel, and one overlapped portion 17 of the flexible outer bag 3 is divided into an overlapping part 17 a and an overlapping part 17 b without joining through vulcanization and then the overlapping part 17 a is fixed to the anchor bolts 26 of the upstream side row and the overlapping part 17 b is fixed to the anchor bolts 27 of the downstream side row, and the flexible inner bag may be disposed in the interior of the flexible outer bag 3. In the flexible outer bag 3 having such a structure, the flexible inner bag can be directly fixed to the river bed concrete, and hence it is useless to form the holes passing the anchor bolts for the fixation of the flexible inner bag in the flexible outer bag 3, so that there is not caused the damage of the flexible outer bag 3.

FIG. 5 is a section view of the flexible membrane weir according to the second embodiment of the invention. In the flexible membrane weir of the second embodiment, the flexible outer bag and the flexible inner bag are fixed onto the river bed concrete and both slope portions at one place through the anchor bolts and the fixing bracket. The other structure is the same as in the flexible membrane weir of the first embodiment.

In this case, the anchor bolts 13 are arranged on the river bed concrete 10 and both the slope portions at predetermined intervals over a full length in the widthwise direction of the water channel. The flexible outer bag 3 and the flexible inner bag 4 are hermetically fixed on the river bed concrete 10 and slope portions by dividing one overlapped portion 17 of the flexible outer bag 3 into an overlapping part 17 a and an overlapping part 17 b and sandwiching the overlapped portion 19 of the flexible inner bag 4 between the overlapping parts 17 a and 17 b, passing bolt holes of the overlapping parts 17 a, 17 b of the flexible outer bag 3 and bolt holes of the overlapped portion 19 of the flexible inner bag 4 and the fixing bracket 15 through the anchor bolts 13 and then screwing nuts 21.

When the flexible inner bag is added to the existing flexible membrane weir consisting of the flexible outer bag, the strengths of the anchor bolt and fixing bracket should be durable to the double structure of the overlapped portions 17, 19. On the other hand, when the whole of the flexible membrane weir is newly prepared, there become an economical method because it is enough to properly design the strengths of the anchor bolt and the fixing bracket.

In the flexible membrane weir according to the above embodiments of the invention, even if cracking is caused in a part of the flexible outer bag by the collision with bounding stone, driftwood, other floating objects and the like to leak out the fluid from the interior thereof, the weir height can be kept at a certain level without deflation owing to the presence of the flexible inner bag. Therefore, water stemmed at the upstream side does not violently flow into the downstream side and the serious disaster is not caused. Also, the flexible inner bag is accommodated and arranged in the interior of the flexible outer bag, so that the flexible inner bag serves as a core body to suppress the occurrence of V-notch in the flexible membrane weir such as local fall-down or the like. Furthermore, since the flexible inner bag is fixed to the river bed through the anchor bolts arranged on the river bed, even if the flexible outer bag is largely broken, the flexible inner bag never comes out toward the downstream side. Moreover, even when the cracks are generated in the flexible outer bag to leak out the fluid from the interior thereof, the flexible outer bag is deflated to copy the form of the flexible inner bag, so that the abnormal state of the outer bag can be found by visual monitoring to immediately take measures. 

1. A flexible membrane weir comprising a lengthy flexible outer bag arranged so as to extend in a widthwise direction of a water channel and inflating by supplying a fluid into an inside thereof and deflating by draining the fluid from the interior thereof, and a lengthy flexible inner bag accommodated and arranged in the interior of the flexible outer bag and capable of arranging fluid supply and drain independently of the fluid supply and drain in the flexible outer bag.
 2. A flexible membrane weir according to claim 1, wherein the flexible inner bag has a height corresponding to 0.5-0.9 times a height of the flexible outer bag.
 3. A flexible membrane weir according to claim 1, wherein the flexible inner bag has an internal pressure higher than that of the flexible outer bag.
 4. A flexible membrane weir according to claim 3, wherein the flexible inner bag has a differential pressure of 2-10 kPa with respect to the flexible outer bag.
 5. A flexible membrane weir according to claim 1, wherein the flexible outer bag is hermetically fixed onto a river bed concrete and slope portions by disposing two rows of anchor bolts on the river bed concrete and both the slope portions at predetermined intervals over a full length in the widthwise direction of the water channel and passing holes for fixation of an overlapped portion of the flexible outer bag and a fixing bracket through the anchor bolts of the first row and screwing nuts and passing the anchor bolts of the second row through another holes formed in the flexible outer bag, and the flexible inner bag 4 is hermetically fixed onto the river bed concrete and slope portions inside the flexible outer bag by passing holes for fixation of an overlapped portion of the flexible inner bag and another fixing bracket through the anchor bolts of the second row and screwing nuts.
 6. A flexible membrane weir according to claim 1, wherein the flexible outer bag is hermetically fixed onto a river bed concrete and slope portions by disposing two rows of anchor bolts on the river bed concrete and both the slope portions at predetermined intervals over a full length in the widthwise direction of the water channel and passing the anchor bolts of the first row through holes formed in one overlapping part constituting one overlapped portion of the flexible outer bag and passing the anchor bolts of the second row through holes formed in the other overlapping part 17 constituting the overlapped portion of the outer flexible bag and screwing nuts onto these anchor bolts through fixing brackets, and the flexible inner bag is disposed in the interior of the flexible outer bag.
 7. A flexible membrane weir according to claim 1, wherein the flexible outer bag and the flexible inner bag are hermetically fixed onto a river bed concrete and slope portions by disposing one row of anchor bolts on the river bed concrete and both the slope portions at predetermined intervals and dividing an overlapped portion of the flexible outer bag into two overlapping parts and sandwiching an overlapped portion of the flexible inner bag between these overlapping parts of the flexible outer bag and passing these anchor bolts through holes formed in such sandwiched portion of the flexible outer and inner bags and screwing nuts onto the anchor bolts through a fixing bracket. 